Modified diffused ink jet printer

ABSTRACT

A plurality of nozzles are connected to a common manifold supplying ink under pressure. Individual nozzle electrodes are either grounded or connected to a source of potential. A common loop electrode between the nozzles and a document is connected to a source of potential. Streams from grounded nozzles are dispersed into a mist which is blocked by a shield having orifices aligned with the nozzles so as to provide selective printing for a matrix type printer.

United States Patent [191 Meier et al.

[111 3,832,719 [451 Aug. 27, 1974 MODIFIED DIFFUSED INK JET PRINTERlnventors: Johann H. Meier; Walter T.

Pimbley, both of Vestal, NY.

Assignee: International Business Machines Corporation, Armonk, NY.Filed: Apr. 21, 1972 Appl. No.: 246,192

US. Cl. 346/75 Int. Cl G01d 15/18 Field of Search 346/75 ReferencesCited UNITED STATES'PATENTS 12/1968 Hertz et a1. 346/75 3,737,914 6/1973Hertz 346/75 Primary Examiner-Joseph W. Hartary Attorney, Agent, orFirm-Francis V. Giolma [57] ABSTRACT A plurality of nozzles areconnected to a common manifold supplying ink under pressure. Individualnozzle electrodes are either grounded or connected to a source ofpotential. A common loop electrode between the nozzles and a document isconnected to a source of potential. Streams from grounded nozzles aredispersed into a mist which is blocked by a shield having orificesaligned with the nozzles so as to provide selective printing for amatrix type printer.

1 Claim, 2 Drawing Figures spaced nozzles l MODIFIEDDIFFUSED INK JETPRINTER FIELD OF THE INVENTION scribes an ink jet recorder in which anelectrode positioned between a nozzle and a document disperses the inkjet from,the nozzle to prevent the stream passing through a shield tomark a document.

SUMMARY OF THE INVENTION Generally stated, it is an object of thisinvention to provide for selective printing from a row of closelyspacednozzlesin a matrix ink jetprinter.

Another object of the invention is to provide for selectivelycontrolling different ones of a plurality of closely-spaced ink jetnozzles for printing characters.

Yet another object'of the invention is to provide for using a commonloop electrode with a plurality of closely-spaced ink nozzles which areconductive and may be selectively grounded or connected to a voltagesource.

It is also an object of the invention to provide for having a commonmanifold with a plurality of closelyconnected thereto which havegrounded connections at the common manifold end and conductive portionsat the other ends which are selectively connected to ground or to asource of potential for controlling the individual ink jet streams.

The foregoing and other objects, features, and advantages of theinvention will be apparent from the following more particulardescription of a preferred embodiment of the invention, as illustratedin the accompanying drawing. 1

DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a schematic isometric view in part of an ink jet printingsystem embodying the invention in one of its forms; and

FIG. 2 is a sectional view in part of the manifold of FIG. 1 taken alongthe line 22.

DESCRIPTION OF A PREFERRED EMBODIMENT I Referring to FIG. 1, thereference numeral 10 denotes generally an ink jet matrix printer systemwhich is shown schematically and comprises a manifold structure 12having a plurality of closely-spaced nozzles Ila-for producing ink jetstreams in response to the supply of ink under pressure to the manifoldthrough a terposed between the electrode 16 and the document forpreventing dispersed streams from marking the doc ument. The mask may beprovided with a plurality of openings 15a-15e aligned with the ink jetsfor permitting the passage of ink jet streams therethrough.

Referring to FIG. 2, it will be seen that the nozzles 11 may compriserelatively fine tubes or bores connecting with a common plenum chamber17 and are 'represented by the tubes Ila-11c. The non-conducting tubesIla-11c may be provided with conducting sleeves 22a-22c at the endsadjacent the plenum chamber, being either separate metal inserts orformed by internal plating of the tubes. These sleeves may be connectedtogether and connected to ground. At the other ends of the tubes lla-llc conducting sleeves represented by the sleeves 24a-24c may beprovided, which may also be separately formed or by internal plating ofthe tubes and which may be selectively connected either to a source ofpotential or to ground, as by means of individual switches 28a-28econnected to the sleeves by means of conductors 26a-26e, as shown inFIG. 1. The tubes lla-l lshould be dimensioned so that with the ink usedthere is a resistance of 0.1 to I megohm between the sleeves 22 and thesleeves 24. With a ing is not to occur, depending on the time constantsof e the system and the desired time on for printing, it may be possibleto let the selectively chargeable nozzles float if printing is not tooccur.

As shown in FIG. 1, the loop electrode 16 is connected to a source ofpotential on the order of .500 volts and if it is desired to print dotsat 14a, 14c, 14d, Me and 14f but not at 14b, theswitch 28b may beconnected to ground while the switches 28a and 28b-28f may be connectedto the 500 volt source. Under these conditions the stream from thenozzle llb'will disperse in the area-of the electrode 16, and the shield15 will prevent thisv stream from marking the document 14. The streams,from the nozzles 11a and 110-1 1 f will continue through the openings15a and l5c-15fto mark the document 14, as shown at 14a and 14c-e.

As an alternate to this arrangement, the manifold 12 can be kept at thehigh potential and the loop electrode 16 at ground potential as shown bythe dotted connectential so that the stream disintegrates at the loopelecconduit 13. The streams are disposed'to provide individual dots on adocument 14, represented by the dots:

14a, 14c, 14d, and Me, in order to print characters thereon.

In order to provide for selectively controlling the ink I jet streams.for printing characters on the document 14, an electrode '16 isprovided for effecting dispersal of unwanted streams. The electrode 16may, for example, comprise parallel plates or a'loop, as shown,connected to a source of electric potential on the order of -500 volts,for example. A mask or shield 15 is introde 16. For printing to occur anindividual nozzle will be grounded so that the stream passes intactthrough the loop electrode 16 and impacts the document 14.

The above-described arrangement operates in accordance with thephenomenon described in the Hertz et al U.S..Pat. No. 3,416,153 and isdue to the well-known property of a jet of liquid to part into dropletssoon after leaving the nozzle due to action of surface tension. When anelectrode is placed around the jet near the point of drop formation anda voltage is applied between the liquid and the electrode, the drops areelec- 1 trically charged due'to the influence of the field. Thiselectric charge gives rise to an electric force on the drop surfacehaving the opposite direction to the dropconserving force of surfacetension. If this electric force becomes larger than the force due tosurface tension, the drops will explode into smaller drops. Since eachof the droplets still are carrying a charge of equal sign, they willrepel each other more or less perpendicularly to the original directionof the jet, thus forming a spray and causing dispersal of the jetstream.

As described in the Hertz patent, with a nozzle having an inner-diameterof 0.015 millimeters from which nozzle a jet of liquid is dischargedunder a pressure of about kilograms per square centimeter with avelocity of about 1,000 centimeters per second, the point of dropformation is situated about 1 millimeter in front of the nozzle. Anyvoltage larger than 90 volts caused the drops to explode. A voltagerange of from 100-500 volts was found to be satisfactory.

From the above description and the accompanying drawing it will be seenthat there is provided an arrangement for selectively printing with aplurality of closely-spaced jets on a document. This lends itselfreadily to a matrix type of character printing, relative movement of thedocument and the nozzles providing the completion of the matrix in theother direction, in this case, in the horizontal direction.

While the invention has been particularly shown and described withreference to a preferred embodiment thereof, it will be understood bythose skilled in the art that various changes in the form and detailsmay be made therein without departing from the spirit and scope of theinvention.

What is claimed is:

1. In an ink jet printer;

a common manifold structure having a common plenum chamber with means tosupply ink thereto under pressure and having a plurality of passagesdefined by a plurality of non-conducting tubes each connected thereto atone end and having a nozzle at the other end to direct streams of inktoward a document,

common electrode means for each of said nonconducting tubes positionedat said common plenum end and connected together to one terminal of asource of electrical potential,

electrode means individual to each nozzle end comprising a conductiveportion at the end of said nozzle away from said manifold and havingswitch means selectively operable to connect said individual electrodemeans to the other terminal of said electrical source and to said oneterminal,

a single electrode means common to all of said nozzles positioned inspaced relation with said individual electrode means between saidindividual electrode means and said document and connected to said oneterminal of said common source of electric potential to disperse the inkstream from an individual nozzle electrode means connected to said otherterminal of said source of potential, and

a mask having openings aligned with said nozzles positioned betweensaidsingle electrode means and said document to permit passage of anondispersed ink stream.

1. In an ink jet printer; a common manifold structure having a commonplenum chamber with means to supply ink thereto under pressure andhaving a plurality of passages defined by a plurality of non-conductingtubes each connected thereto at one end and having a nozzle at the otherend to direct streams of ink toward a document, common electrode meansfor each of said non-conducting tubes positioned at said common plenumend and connected together to one terminal of a source of electricalpotential, electrode means individual to each nozzle end comprising aconductive portion at the end of said nozzle away from said manifold andhaving switch means selectively operable to connect said individualelectrode means to the other terminal of said electrical source and tosaid one terminal, a single electrode means common to all of saidnozzles positioned in spaced relation with said individual electrodemeans between said individual electrode means and said document andconnected to said one terminal of said common source of electricpotential to disperse the ink stream from an individual nozzle electrodemeans connected to said other terminal of said source of potential, anda mask having openings aligned with said nozzles positioned between saidsingle electrode means and said document to permit passage of anon-dispersed ink stream.